Time delay fuze



G. WEBB T IME DELAY FUZE July 19, 1966 2 Sheets-Sheet 1 Filed Nov. 22, 1963 INVENTOR.

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G. WEBB July 19, 1966 TIME DELAY FUZE 2 Sheets-Sheet 2 Filed NOV. 22, 1963 INVENTOR. GEORGE WEBB /flflw. @4424 gflmum.

ATTORNEYS.

3,261,293 TIME DELAY FUZE George Webb, Richmond, lnd., assignor to Avco Corporation, Richmond, Ind., a corporation of Delaware Filed Nov. 22, 1963, Ser. No. 325,727

6 Claims. (Cl. 10282) The present invention relates to ordnance, and specifically to a time delay fuze which may be triggered by mechanical, electrical, pneumatic, or hydraulic means. The fuze can be employed to fire a primer or detonator or to open or close a switch or valve. Also, the basic device can be used to provide various time delays or to function in the manner of an integrating accelerometer. A preferred embodiment is described herein.

The invention provides a novel spring-driven fuze which uses a fluid working medium contained in a closed system to provide the desired time delay. When the required delay is achieved, the spring is tripped and its energy used to fire a primary explosive such as a primer or detonator.

A primary object of the invention is to provide a simple mechanically driven fuze which is so integrated that a maximum number of functions can be performed with a minimum number of parts.

Other objects of the invention are to provide:

(1) A time delay fuze adjustable for various time delays;

(2) A fuze which can be designed to act as an integrating accelerometer;

(3) An economical fuze which can be used to trigger mines, hand grenades, and specialized explosive devices such as switches, valves, actuators, and cable cutters;

(4) A fuze which contains th working media in a closed system which can be tested to afford before-thefact reliability data when required;

(5) A fuzewhich can be driven by spring, gas, liquid, inertia, or solenoid forces.

For a better understanding of the invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following description of the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a grenade to the base of which there is fitted a fuze in accordance with the invention;

FIGS. 2, 4, and 5 are longitudinal sectional views of my improved fuze showing the parts in the following phases of operation, respectively: safe, firing pin and plunger moving toward the armed position, and firing position; and

FIG. 3 is a cross-sectional view taken along the section line 3--3 of FIG. 2, looking in the direction of the arrows.

The component parts of a fuze in accordance with the invention are housed in a cylindrical aluminum housing member machined to provide the following formations: a generally circular longitudinal main bore; an inner annular groove 11; a transverse lead-out channel 13; and an enlarged circular recess portion 14. Approximately amidships, and in symmetrical registry with channel 13, the housing is formed with an integral outwardly projecting coupler 15, which is recessed to provide a compartment for a highly explosive lead 16. Coupler 15 attaches to the main device to be exploded (FIG. 1).

Disposed within the housing are a primary explosive pellet or detonator 17 and an aluminum firing pin 18. These are referred to as firing elements. In this embodiment the firing pin moves into the detonator and is the active firing element.

In accordance with the teachings of the invention, there is provided actuating means for exerting a force on the firing pin 18 in a direction appropriate to cause firingi.e., impact of pin 18 on detonator 17. In the particular embodiment shown, this means is a compressed helical spring 19, which is made of steel, seated in a generally nited States Patent 0 cylindrical aluminum cap member 20, and positioned to exert a driving force against firing pin 18 in such a direction as to bias pin 18 toward detonator 17. lt will be undrestood that the term actuating means is intended to cover not only a spring, but also any driving means which can be designed to operate in accordance with a mathematical function of time, energy, or force. It will be noted that the plug 20 is located at one end (right, FIG. 2) of the main internal bore of housing 10. The extent of the projection of this plug into such bore can be adjusted, as by screw-threading or press-fitting, to vary the force on the firing pin 18.

Further in accordance with the invention, the detonator is disposed within an aluminum slider or plunger member 21, which is concentrically and slidably mounted within said main bore and machined with the following formations: a solid face portion 22; a longitudinally centrally bored extension 23, formed to receive concentrically the detonator 17 and the relatively slidable firing pin 18; a transverse lead-out channel 24; a pair of diametrically opposed locking-ball tunnels 25 and 26; and a longitudinally extending locator groove 27, into which the locator pin 12 projects. Seated between the tunnels 25 and 26 and a wide-radius annular groove 28 formed in the firing pin member 18 are a pair of steel locking balls 29 and 30, the function of which is to confine the firing pin 18, in response to pressure of spring 19, to conjoint movement with the plunger 21, so long as the wall of the main bore of the housing is forcing the locking walls 29 and 30 into engagement with the groove on firing pin 18. That is, the firing pin is locked by balls 29 and 30 during the arming cycle, when the plunger element is driven by the spring.

The housing 10 and plunger 21 are further formed with small registering transverse bores adapted to receive a stainless steel locking wire 31, which maintains safety during storage and is withdrawn for purposes of initiating arming of the fuze.

It will be understood from the description up to this point that, when the locking wire 31 is removed, the plunger 21 moves outwardly (i.e., to the left as shown in FIG. 2) under the force of spring 19, that force being exerted through the rear portion of the firing pin member 18 and the locking balls 29 and 30 on the plunger 21, and moving the latter outwardly in accordance with the functional characteristics of the actuating means 19, the setting of the plug 20, and the resistance against which plunger 21 Works. When plunger 22 has moved sufficiently outward (FIG. 5) to register the tunnels 25 and 26 with the annular groove 11 in the housing, the locking balls 29 and 30 are cammed laterally outwardly, freeing the firing pin 18, so that the latter is immediately driven into detonator 17, thereby initiating firing, the then registering ports 24 and 13 establishing communication between the detonator 17 and the chamber which contains the high explosive element 16. The function of the locator pin 12 and longitudinal groove 27 is simply to prevent rotation of the plunger 21.

The discussion is now directed to the time-delay determinants of the action just described.

In accordance with the invention, there is mounted, within the main bore of the housing 10 and in abutment with face 22, a cylindrical silicon rubber roll bellows member 32, which is formed with an outwardly extending flange 33 recessed in the enlarged portion of the bore of the housing. Tightly abutting this flange is a sintered metal gas-permeable filter or diaphram element 34, flatfaced and circular in configuration.

The reference numeral 35 designates the working fluid, which can be either a liquid or a gas, a liquid such as mercury or silicon fluid being preferred in applications wherein shock or vibration or long delay times are antici- [MILK], This fluid 35 is contained within the bellows 32. the reference numeral 36 designates a silicon rubber seal secured in place by an aluminum retaining ring 37 in order to provide a closed system, which has the advantages of long titne storage and reliability.

Returning now to the discussion of the operation of the invention:

The time at which arming and firing occur is delayed by the resistance encountered by face 22 of the plunger 2|. This face compresses the bellows 32, which forces the fluid 35 through the orifice 34 to provide the delay action. Accordingly, the plunger moves slowly until the locking balls 29 and 30 are in line with the groove 11 in the housing 10. Upon reaching such alignment, the firing pin member 18 is unlocked and is driven into the detonator [7. Particular attention is invited to the fact that at this time the channels 24 and 13 are in registry, so that the primary explosive or low-explosive detonator is in fully armed position so far as communication with high explosive 16 is concerned.

Numerous parameters can be changed to give the required delay time: filter size, pore size in element 34, pore density in element 34, filter length, plunger stroke, bellows diameter, fluid viscosity, and driving force. Plug 24) can be a threaded member which can be adjusted at time of use. The delay working media system (parts 32, 34, 35, 36, and 37) can be contained in a separate housing portion which may be threaded to the remainder of the housing to give adjustable stroke length at time of use. Also, spring 19 can be replaced with a weight which is subject to an accelerating force to provide for the integration of time multiplied by force, since this system can be made to give fiow rates which are functions of driving force. Primer 17 and firing pin 18 can be replaced with switch-contact firing elements to provide for a delay switch with snap action.

While there has been shown and described what is at present considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various modifications and changes may be made therein without departing from the scope of the invention as defined by the appended claims.

I claim:

1. A time delay fuze comprising:

a housing;

a driven element mounted wit'hin said housing;

an explosive charge within said dniven element;

means including a fluid-permeable element for opposing the displacement of said driven element as a function of time;

a firing pin within said driven element;

actuating means consisting of a single spring tending to drive the firing pin into firing position; and

means for normally locking the firing pin and the driven element against relative displacement;

the spring being disposed between the firing pin and the housing so that the spring drives both the firing pin and the driven element toward the fluid-permeable element;

the locking means and the housing being so formed and arranged that after a predetermined displacement of the driven element the locking means is released from the firing pin to permit the latter to be driven by the spring against the explosive charge;

the housing and driven elements being formed with lead-out channels which do not register to arm the fuze until said displacement is substantially completed.

2. A time delay fuze comprising, in combination:

a T shaped housing formed with an axial bore, a transverse lead-out channel terminating in a coupling, and an annular interior groove axially displaced from said channel;

a plunger member mounted within said bore and comprising a solid face and a. tubular extension formed with a lead-out channel immediately behind said face and a pair of transverse tunnels;

a primary explosive disposed be-hind said face and within said plunger member;

a firing pin member comprising a spool-shaped body having an axially extending projecting point and an annular exterior groove;

locking balls disposed in said tunnels and normally abutting against said exterior groove and the wall of said bore to lock the firing pin member to said plunger member;

a spring-seat member adjustably fitted in one end of said bore;

a compression spring disposed between said seat and said firing pin member for driving said firing pin member toward said explosive;

a withdrawable wire for preventing movement of said plunger member;

and means for controlling movement of said plunger member when said wire is withdrawn, comprising:

a flexible bellows member within said bore and having a closed end in abutment with said face;

fluid contained in said bellows member;

orifice means disposed adjacent the other end of said bellows member;

and a cap member for closing the end of the bore adjacent said orifice means;

said plunger member moving to contract the bellows member to force fluid through said orifice means until said channels register and until said locking balls are cammed into said interior groove to free the firing pin member to impact the primary explosive, whereupon said registering channels then provide communication between said :firing explosive and the remainder of a firing train.

3. A time delay fuze comprising:

a housing;

a driven element formed as a solid-faced plunger having a hollow extension and mounted within said house;

an explosive change within said driven element;

means comprising a roll bellows and a fluid-permeable element for limiting the displacement of said driven element as a function of time, said roll bellows being adapted to contain fluid and having one end in contact with the solid face of the plunger and another end closed by said fluid-permeable element;

a firing pin within said driven element;

actuating means tending to drive the firing pin into firing position; and

means for normally locking the firing pin and the driven element against relative displacement;

the locking means and the housing being so formed and arranged that after a predetermined displacement of the driven element the locking means is released from the firing pin to permit the latter to impact against the explosive charge;

the housing and driven elements being formed with lead-out channels which do not register to arm the fuze until said displacement is substantially completed.

4. A time delay t'uze in accordance with claim 3 in which the explosive charge is seated in said extension, and the firing pin is slidably mounted in said extension.

5. A time delay fuze in accordance with claim 4 in which the actuating means is a compression spring,

and an adjustable seat for varying the thrust of said spring.

6. A time delay fuze in accordance with claim 5 in which the firing pin is formed with an annular groove,

in which the extension is formed with transverse tunnels,

and in which the locking means comprises locking b11115 disposed in said tunnels and in abutment with said groove.

References Cited by the Examiner UNITED STATES PATENTS Smith 102-82 Leonard 10282 Haberland 102-16 Voland 102-82 X Ono 10270 Stott 102-70 6 1/1964 Jmsc 10Z82 X 7/1965 Kalaf 102--16 FOREIGN PATENTS 8/1956 France.

8/1960 Germany. 6/1944 Great Britain.

BENJAMIN A. BORCHELT, Primary Exaim'm'r.

10 SAMUEL FEINBERG, Examiner.

G. L. PETERSON, G. H. GLANZMAN,

Assistant Exam filers. 

1. A TIME DELAY FUZE COMPRISING: A HOUSING; AN DRIVEN ELEMENT MOUNTED WITHIN SAID DRIVEN ELEMENT; AN EXPLOSIVE CHARGE WITHIN SAID DRIVEN ELEMENT; MEANS INCLUDING A FLUID-PERMEABLE ELEMENT FOR OPPOSING THE DISPLACEMENT OF SAID DRIVEN ELEMENT AS A FUNCTION OF TIME; A FIRING PIN WITHIN SAID DRIVEN ELEMENT; ACTUATING MEANS CONSISTING OF A SINGLE SPRING TENDING TO DRIVE THE FIRING PIN INTO FIRING POSITION; AND MEANS FOR NORMALLY LOCKING THE FIRING PIN AND THE DRIVEN ELEMENTS AGAINST RELATIVE DISPLACEMENT; THE SPRING BEING DISPOSED BETWEEN THE FIRING PIN AND THE HOUSING SO THAT THE SPRING DRIVES BOTH THE FIRING PIN AND THE DRIVEN ELEMENT TOWARD TEH FLUID-PERMEABLE ELEMENT; THE LOCKING MEANS AND THE HOUSING BEING SO FORMED AND ARRANGED THAT AFTER A PREDETERMINED DISPLACEMENT OF THE DRIVEN ELEMENT THE LOCKING MEANS IS RELEASED FROM THE FIRING PIN TO PERMIT THE LATTER TO BE DRIVEN BY THE SPRING AGAINST THE EXPLOSIVE CHARGE; THE HOUSING AND DRIVEN ELEMENTS BEING FORMED WITH LEAD-OUT CHANNLES WHICH TO NOT REGISTER TO ARM THE FUZE UNTIL SAID DISPLACEMENT IS SUBSTANTIALLY COMPLETED. 